xfactor_pitbulls

iTrader: (16)

I am sure most folks have this worked out, but here it is for anyone curious. I checked my math with autocad and enclosed the picture in a PDF. Basically if you upgrade from say a 2.00 to a 2.05 you obviously gain .05". Divide that by 2 to get your measurement. Now you consider the angle of 15 degrees, which just so happens to fall incrementally into the 15,30,45,60,75,90 usual degree ranges. If the valve entered the head at 90 degrees it would decrease PTVC clearance by .025, if it entered at 0 degrees it would not decrease the number at all. 45 degrees is in the middle and would have an impact of .0125". We are at 15 degrees so you would actually divide by 2 again to get the actual number of .00625". I hope that helps someone. BTW my math says a difference of .00625 and the drawing shows .0065, so this is close enough.

Brandon

1fastWS6

iTrader: (3)

Thats correct. Simple geometry gets you the same answer too. .025" x tangent 15* = .0067".

I'm not sure why so many people freak out about losing P-V clearance with bigger valves. It's obviously not that big of a reduction from a stock valve to a big 2.05.